// +build windows

/*
 *    Copyright (c) 2018 Unrud<unrud@outlook.com>
 *
 *    This file is part of Remote-Touchpad.
 *
 *    Foobar is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    Remote-Touchpad is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
 */

package main

import (
	"errors"
	"syscall"
	"unsafe"
)

const (
	inputMouse    uintptr = 0x0
	inputKeyboard uintptr = 0x1

	keyeventfKeyup   uint32 = 0x2
	keyeventfUnicode uint32 = 0x4

	mouseeventfMove       uint32 = 0x1
	mouseeventfLeftdown   uint32 = 0x2
	mouseeventfLeftup     uint32 = 0x4
	mouseeventfRightdown  uint32 = 0x8
	mouseeventfRightup    uint32 = 0x10
	mouseeventfMiddledown uint32 = 0x20
	mouseeventfMiddleup   uint32 = 0x40
	mouseeventfWheel      uint32 = 0x800
	mouseeventfHwheel     uint32 = 0x1000

	wheelDelta int = 120
)

type mouseInput struct {
	typ uintptr // HACK: padded uint32

	dx, dy                   int32
	mouseData, dwFlags, time uint32
	dwExtraInfo              uintptr
}

type keybdInput struct {
	typ uintptr // HACK: padded uint32

	wVk, wScan    uint16
	dwFlags, time uint32
	dwExtraInfo   uintptr

	padding [8]byte
}

type windowsPlugin struct {
	userDLL       *syscall.LazyDLL
	sendInputProc *syscall.LazyProc
}

func InitWindowsPlugin() (Plugin, error) {
	p := &windowsPlugin{}
	p.userDLL = syscall.NewLazyDLL("user32.dll")
	p.sendInputProc = p.userDLL.NewProc("SendInput")
	if err := p.sendInputProc.Find(); err != nil {
		return nil, UnsupportedPlatformError{err}
	}
	return p, nil
}

func (p *windowsPlugin) Close() error {
	return nil
}

func (p *windowsPlugin) KeyboardText(text string) error {
	runes := []rune(text)
	if len(runes) == 0 {
		return nil
	}
	inputs := make([]keybdInput, len(runes)*2)
	for i := range inputs {
		inputs[i].typ = inputKeyboard
		inputs[i].wScan = uint16(runes[i/2])
		inputs[i].dwFlags = keyeventfUnicode
		if i%2 == 1 {
			inputs[i].dwFlags |= keyeventfKeyup
		}
	}
	if r, _, err := p.sendInputProc.Call(uintptr(len(inputs)),
		uintptr(unsafe.Pointer(&inputs[0])),
		unsafe.Sizeof(inputs[0])); int(r) != len(inputs) {
		return err
	}
	return nil
}

func (p *windowsPlugin) PointerButton(button uint, press bool) error {
	input := mouseInput{
		typ: inputMouse,
	}
	if button == 1 && press {
		input.dwFlags = mouseeventfLeftdown
	} else if button == 1 {
		input.dwFlags = mouseeventfLeftup
	} else if button == 2 && press {
		input.dwFlags = mouseeventfMiddledown
	} else if button == 2 {
		input.dwFlags = mouseeventfMiddleup
	} else if button == 3 && press {
		input.dwFlags = mouseeventfRightdown
	} else if button == 3 {
		input.dwFlags = mouseeventfRightup
	} else {
		return errors.New("unsupported pointer button")
	}
	if r, _, err := p.sendInputProc.Call(1, uintptr(unsafe.Pointer(&input)),
		unsafe.Sizeof(input)); int(r) != 1 {
		return err
	}
	return nil
}

func (p *windowsPlugin) PointerMove(deltaX, deltaY int) error {
	input := mouseInput{
		typ:     inputMouse,
		dx:      int32(deltaX),
		dy:      int32(deltaY),
		dwFlags: mouseeventfMove,
	}
	if r, _, err := p.sendInputProc.Call(1, uintptr(unsafe.Pointer(&input)),
		unsafe.Sizeof(input)); int(r) != 1 {
		return err
	}
	return nil
}

func (p *windowsPlugin) PointerScroll(stepsHorizontal, stepsVertical int) error {
	inputs := make([]mouseInput, 0, 2)
	if stepsHorizontal != 0 {
		inputs = append(inputs, mouseInput{
			typ:       inputMouse,
			dwFlags:   mouseeventfHwheel,
			mouseData: uint32(stepsHorizontal * wheelDelta),
		})
	}
	if stepsVertical != 0 {
		inputs = append(inputs, mouseInput{
			typ:       inputMouse,
			dwFlags:   mouseeventfWheel,
			mouseData: uint32(stepsVertical * wheelDelta),
		})
	}
	if len(inputs) == 0 {
		return nil
	}
	if r, _, err := p.sendInputProc.Call(uintptr(len(inputs)),
		uintptr(unsafe.Pointer(&inputs[0])),
		unsafe.Sizeof(inputs[0])); int(r) != len(inputs) {
		return err
	}
	return nil
}